Co-morbidity and familial aggregation of alcoholism and anxiety disorders

BACKGROUND: This study examined the patterns of familial aggregation and co-morbidity of alcoholism and anxiety disorders in the relatives of 165 probands selected for alcoholism and/or anxiety disorders compared to those of 61 unaffected controls. METHODS: Probands were either selected from treatment settings or at random from the community. DSM-III-R diagnoses were obtained for all probands and their 1053 first-degree relatives, based on direct interview or family history information. RESULTS: The findings indicate that: (1) alcoholism was associated with anxiety disorders in the relatives, particularly among females; (2) both alcoholism and anxiety disorders were highly familial; (3) the familial aggregation of alcoholism was attributable to alcohol dependence rather than to alcohol abuse, particularly among male relatives; and (4) the the pattern of co-aggregation of alcohol dependence and anxiety disorders in families differed according to the subtype of anxiety disorder; there was evidence of a partly shared diathesis underlying panic and alcoholism, whereas social phobia and alcoholism tended to aggregate independently. CONCLUSIONS: The finding that the onset of social phobia tended to precede that of alcoholism, when taken together with the independence of familial aggregation of social phobia and alcoholism support a self-medication hypothesis as the explanation for the co-occurrence of social phobia and alcoholism. In contrast, the lack of a systematic pattern in the order of onset of panic and alcoholism among subjects with both disorders as well as evidence for shared underlying familial risk factors suggests that co-morbidity between panic disorder and alcoholism is not a consequence of self-medication of panic symptoms. The results of this study emphasize the importance of examining co-morbid disorders and subtypes thereof in identifying sources of heterogeneity in the pathogenesis of alcoholism.